1. Field
Embodiments of the present invention relate generally to gas turbine engines, and in particular, to a method and apparatus for attaching a transition duct to a turbine section in a gas turbine engine.
2. Description of the Related Art
A conventional gas turbine engine includes a compressor section, a combustion section including a plurality of combustors, and a turbine section. Ambient air is compressed in the compressor section and conveyed to the combustors in the combustion section. The combustors combine the compressed air with a fuel and ignite the mixture creating combustion products defining hot working gases that flow in a turbulent manner and at a high velocity. The working gases are routed to the turbine section via a plurality of transition ducts. Within the turbine section are rows of stationary vane assemblies and rotating blade assemblies. The rotating blade assemblies are coupled to a turbine rotor. As the working gases expand through the turbine section, the working gases cause the blades assemblies, and therefore the turbine rotor, to rotate. The turbine rotor may be linked to an electric generator, wherein the rotation of the turbine rotor can be used to produce electricity in the generator.
The transition ducts are positioned adjacent to the combustors and route the working gases from the combustors into the turbine section through turbine inlet structure associated with a first row vane assembly. The vane assembly is mounted on an annular vane carrier. The transition duct comprises an aft frame defining a transition exit that opens into the gas turbine section.
A transition duct may be assembled on the aft side by fastening the transition aft frame to the vane carrier. For this purpose, the forward face of the vane carrier contains axially extending threaded holes or holes comprising threaded inserts, spaced appropriately to align with the transition aft frame. The transition aft frame is then bolted to the vane carrier.
However, providing threaded features in the vane carrier may negatively affect the life of vane carrier as the threads tend to wear off over time particularly due to repeated servicing of the parts. Also, removal and replacement of threaded inserts during service can be time consuming and have an adverse effect on overall outage time.